Study And Design Of Control System On Fruit And Vegetable Drying Device

Recent years in China has witnessed growing scale of fruits and vegetablesproduction. However, fresh fruits and vegetables deteriorate and rot with time passing by. Therefore, the color, taste,shapes and active ingredient of dehydrated fruits and vegetables which are characterized by rot-free, transportation convenience and appreciation are capable of reservation. Based on drying process requirement of fruits and vegetables, Mechanical and Electrical Engineering College of Shaanxi University of Science and Technology has developed a new fruit and vegetable drying equipment which enjoys energy-conservation, environmental protection and significant economic benefits.In this thesis, based on the design backgrond of the production of Shan xi University of Science and Technology fruit and vegetable dryer control system, analyzed and discussed fruit and vegetable drying process control, design a set of control system based on PLC. Which can switch between manual and automatic operztion, motor sequence control, Detection and solve fault, acquisition and processing the parameters of pressure, humidity, wind speed.According to the temperature control has object complexity, electric heating lag, nonlinear, and time-varying characteristics, this artiele analyzes the PID controller and fuzzy eontroller and their classifieation, design a fuzzy PID controller combine the PID controler and fuzzy contoler. Through design the fuzzy controllerstructure, the input-output subordination functions selection, and the tables of the fuzzy control rules establishment, completed the controller design, ensure temperature parametesstable. Through the toueh screen software designed the monitor and control interfaee, the system has monitoring process date, processing parameters inputting, real-time data acquisition and displaying and historical data downloads funetions.After debugging, the control system meets the expected control requirements and is working well. After analyzing the real-time trends of the dryer temperature monitored by the HMI interface, we future confirmed that the fuzzy PID contr ol can solved the problems we meet in fruit and vegetable dryer temperaturecontrol system, which gives a certain guidance value for the future design of thefruit and vegetable dryercontrol system.